1. Field of the Invention
The present invention relates to an imaging lens, an optical apparatus including the imaging lens and a method for manufacturing the imaging lens.
2. Related Background Art
A macro lens capable of photographing a near-distance object point up to shooting magnification of −1.0 from an infinite-distance object point has hitherto been proposed (refer to, e.g., Japanese Patent Application Laid-Open No. 2000-284171). Further, a general type of macro lens based on a 3-group configuration is a macro lens in which a first lens group and a second lens group configure a double Gaussian type, and a third lens group serving as a rear converter is added just posterior thereto. Particularly, the third lens group is formed as a negative lens group for downsizing in overall length in many cases. Further, over the recent years, increased strictness about ghost images and flare defined as one of factors, which affect not only aberration correction performance but also optical performance, has been requested of the 3-group configuration macro lens capable of photographing the near-distance object point. Therefore, a request for the higher performance is given also to an antireflection coating formed on a lens surface, and a multi-layered film design technique and a multi-layered film growth technique continue their developments (refer to, e.g., Japanese Patent Application Laid-Open No. 2000-356704).
If the third lens group has negative refractive power, however, such a problem arises that an image plane deviates in an object-sided direction due to a strong diverging component on the rear side with the result that a sufficient back focus cannot be ensured. Moreover, focusing is conducted in a way that shifts each lens group toward the object side in many cases, however, it is preferable that the third lens group is formed as a fixed lens group in order to simplify a lens barrel mechanism and increase a degree of freedom.